Implement exponential backoff for failed Me2Me authentication attempts

remoting/protocol/session_manager.h

Index: remoting/protocol/session_manager.h
diff --git a/remoting/protocol/session_manager.h b/remoting/protocol/session_manager.h
index 1a3e8aa4dd267e080f13f442216ce6d234decd10..2cc575914650f4dcc1c1f6daf4eeb79c02a0b1c8 100644
--- a/remoting/protocol/session_manager.h
+++ b/remoting/protocol/session_manager.h
@@ -110,8 +110,18 @@ class SessionManager : public base::NonThreadSafe {
   virtual ~SessionManager() { }
 
   enum IncomingSessionResponse {
+    // Accept the session.
     ACCEPT,
+
+    // Reject the session due to incompatible session configuration.
     INCOMPATIBLE,
+
+    // Reject the session because the host is currently disabled due
+    // to previous login attempts.
+    DISABLED,

[Wez, 2012/03/27 16:23:56]

nit: "DISABLED" seems like a bad name for this, since that's the term we
generally use when the host is stopped (i.e. not online).  "OVERLOAD" or
"UNAVAILABLE" might be better terms.

[Sergey Ulanov, 2012/03/27 18:00:52]

There is HOST_IS_OFFLINE error code that we use to indicate that the host is
offline, so I don't think HOST_IS_DISABLED can be confusing. IMHO distinction
between UNAVAILABLE and OFFLINE is even less clear. 
I've renamed this particular value to UNAVAILABLE, but kept HOST_IS_DISABLED
error code  - changing it now would require merging to the M19 branch as we use
these names for interaction between the client plugin and webapp. We can still
do if you feel strongly about it.

[Wez, 2012/03/27 19:49:41]

If we have "offline" and "disabled" then it's natural for a reader to assume
that DISABLED means the user explicitly disabled the host, and that OFFLINE
means that the host is enabled but not online for some reason.
I'd be fine with OVERLOAD[ED]. ;)

"unavailable" and "offline" have overlapping meanings, but "offline" is pretty
specific - it's saying the host is actually offline.  "unavailable" is more
specific, meaning it's online but not currently available - that might be
re-usable to mean that the host is in-use if we ever wanted to provide
floor-control for access to hosts.
I do think that HOST_IS_DISABLED is a very confusing name - it suggests that the
host is installed & configured, but not enabled right now, rather than that it
has automatically stopped accepting connections.

+
+    // Reject the session because the client is not allowed to connect
+    // to the host.
     DECLINE,
   };